Drying apparatus



Sept. 19, 1944. c. STONE DRYING APPARATUS Filed J1me so, 1941 CARLTON STONE I 'I'NVIENTOR" ATTORNEY Patented Sept. 19,1944 7 s P TENT T e DRYING APPARATUS Carlton Stone, Duncan, British Columbia, Canada Application June 30,1941, Serial No. 400,526

In Canada June 3, 1941 1 Claim. (01.263-41) invention-relatesto apparatu for drying lumber An objectof the present invention is the pro- .yision of lumber drying apparatus which is a complete and independent unit.

Another object is the provision of lumber drying apparatus which does not require a trained and skilled operator. V

Another object is the provision of lumber dryingapparatus with a far greater dryin capacity per cubicfoot of space than-have the kilns now in common use. 7

A further object is the provision of lumber drying apparatu which does not require steam and yet in which the lumber does not become case-hardened.

1 A further object is the provision of apparatus of the naturedescribed ofextremely simple and inexpensive construction,

, In; thelumber drying kilns now in common use-steam is employed to heat air in the kiln which is circulatedthrough. the piledlumber. This necessitates very expensive equipment. A

basement is usually built under the kilns in which are placed great lengths of steam pipes and miexpensive construction operating at lowtemperat-ures, which does *not require any: steam iand, therefore, may be set up at any desiredpoint in relation to the mill. The need for drying lumber is becoming greater every day, as when shipping by rail, the freight per thousand feet of lumber is much less with dry lumber, and with ocean borne lumber, it is a guarantee against discolouration and it is ready for use on arrival, thus commandinga higherprice.

At the present time, the difficulty is that most mills have not the boiler capacity nor the space to put the boilers in that are necessary to do sufficient lumber drying while there are numerous small mills that cannot afford to install expensive dry kiln systems and, therefore, they are completely barred from this market.

merous fans forcirculating air around these pipes andthrough the lumber, said fans andv their bearings operating invery great heat.

This means the kiln must be located close to the boiler of the mill and as the mill is built around the boiler, the size and number of kilns that can be installed are vers limited. Oneof the chief difiiculties is that mills now operating cannot install new kilns because they have not the space available close to their boilers or their.

'fboilers have not the capacity to supply the steam for such a large demand when you consider that a kiln capable of accommodating about 100,000 feet of lumber requires'enough steam to run a complete small mill. Q

must always be available and the kiln must be in the charge of a specially trained operator, known as a kiln man, in orderto operat themwlth any degree of success. These'kilns have to be very well constructed and they must be operated at high temperatures to dry the lumber ina comparatively short time inorder to make them pay. Furthermore, there is a great loss of heat since the heat ,is'flrst transferred to water, converting it into steam, and then from the latter to the air to be circulatedthrough the lumber. There is a great ,lossat leach transference of, the heat.

The chief object of this invention is to provide s umb r n p ratu o ys' e 1 V 40 v Other disadvantages are that a steam engineer This invention overcomes the above-noted dis advantages by providing a kiln in whichthe lumberis piled, means for directly heating andreheating air, and means for circulatin the heated .air through' the lumber in the kiln. Thi unit is complete and compact and it maybe located at .any desired point in relation to the mill. It is preferable-to use sawdust for heating the air, thus utilizing to advantage a fuel which is ordinarily burned just to get rid of it. Neither a steam engineer nor a trained operator is required and it is not necessary to dryithe lumber in a minimum of time. Consequently, it is possible to takemuch longer to dry the lumber, and as a result of this, the kiln may be of much lighter and inexpensive construction. The fuel economy is very great for there is considerable loss in heating water to make steam as compared with the direct applica,--

tion of heat to the drying air. I 7 V In the accompanying drawing,

Figure .1 is a side elevation of the drying,ap

paratus,

Figure 2 is a plan view, partly in section, of the apparatus withoutany lumber piled therein,-

Figure 3 is a vertical'section taken onthe line 3-4 of Figure 1,;

. Figure 4 is an enlarged section taken substantially on the line 4--4 of Figure 1 l Referring more particularly to the drawing, 10 is a drying chamber of any requiredshape, al-' though it i preferably long and narrow, as

shown. This chamber may be of any desired construction but, owing to the nature of this invention, it may be of comparatively light construction, while ithas side walls II and I2, end walls |3and l4, and abase I5.

The drying. chamber is preferably open at :its

top and is provided with a. coverl6 removably mounted thereon. This cover may be formed in one section Or in several sections, as shown, depending upon the length of the drying chamber. It is also possible to have the cover permanently fixed on the chamber, in which case the. end Wall l3 would be in the form of a door. If the side walls II and I2 are lightly constructed, a plurality of heavy vertical supports ll, suchas poles, may be provided for bracing said walls.

One or more valve arrangement H! are provided adjacent the top of either'or both the side walls I I and I2. Each valve arrangement consists of a slide door 20 adapted removablytolcover an opening 2| formed in the side Walls.

Ducts 22 and 23 are mounted in the drying chamber at each side'thereof and preferably adjacent its base 15, said ducts having a plurality of openings 24 formed therein. These ducts may progressively taper towards the end wall l3, as shown.

dryzing :chamber 25 located adjacent the end wall I 4, preferably outside the heating chamber, is mounted on a base 26. A suitable heating-unit isprovided for heating the chamber 25 .and zin theipreferred form .of :the invention, -a sawdust bu'rn'er unit :21 having a hopper 28, is'used for thispurpose. Thisburner unit-is adapted to direct the products ofcombustion through a passage --30 :extending longitudinally of th base ;26, .be-

neath the chamber 25, said passage curving upwardly at 3| to directth productsof combustion t'hrough a plurality of tubes-.32 extending through --the heating chamber; Tl18 tubes32disch'arge the products of combustion into :a smoke *header :33, irom which a stackv 34 projects upwardly.

A hot air-pipe 35 connects :the heating chamber 25 to the duct 22 andia' return' pipe 36 "connects --the duct 23 to afan or blower 31' which, inzturn, -is coniiectd to said heating chamber by .a: pipe -38. Theipipe-35 communicates with the chamber ZS- atthe topto-wards theirearithereof while the -lpipe 38communicates with saidchamber adjacent its forward end. 'Theifan 01 blowerl31 .is driven any suitable 'manner, such as by'anelectricmotor 640' havinglazpu'lleyl I which is sconnectedbyiasbelt i42 to a pulley 43 'mountedzon .the shaft 44 :or. said fan. i

" Pipes 45 a'nd 46 interconnectthe hotzair and return pipes 35 and 38. Control valves-11,18,150 and-'51 arepositiond in the--pipes 35,' 45,"46:; 'nd 36 5 respectively. Figure 4 is l a section through one of these valves in partia'lly open position. Each valve hasaf-valve "plate' 52 which may be raised andlowered to open and close said valve.

"'As thevalves' 4T and'f5 l-ar intende'd to be closed while the valves 48 -and '50- are open and-' vice versa, there maybe one valve plate 52 only for each 'set'of valves. Wliile the valves-shown -are suitable for the purpose, it is to be understood 'thatany"desiredtype of valvemay -be employed.

If desired, suitable meansmay be provided for a supplying steam or atomized water to theh'ot-air pipes 35 or at any other desired point -in the system; should this proveinecessary. An 'exa'mple. of this is illustrated inFigureZ in which a pipe 5 54,: extending from a suitable source I not shown) is adapted to supply steamor -water to one or needs -to *be changed at predetermined intervals.

*morenoz'zles55 located in the hot air pipe. -A

"control'valve' 55 'is-provided the pipe 54."

' Inuse,the lumber ispiledgin thedr-ying cham- "ber [0 in any suitable manner. Ifthe cover l 6' is "removable, and-this is the preferredalternative,

it is removed by means ofacrane and the-lumber f lowered intothe chamber-inbundles. Thislumber extendslo'ng'itudinally of-thechamber and it but it is preferable to employ a fan is piled or bundled with spacers 53 extending transversely thereof. The advantage of this form of the invention, is that the lumber is usually carried from the mill in bundles by cranes and these are deposited at desired points. With this arrangement, these bundles may be picked up and deposited in the drying chamber Without any special or extra piling.

If the roof is permanent, the lumber may be piled on small trucks and wheeled into the chamber, this being the practice nowin common use. 'The diificulty is that the lumber has to be piled on the trucks, entailing extra and specilized labour. Air circulates through the heating chamber 25, the drying chamber I0 and back to said heating ;-chamber. The course of the air through this circuit depends upon the setting of the valves 41, 48,50-and 5|.

With the valves 48 and closed and the valves 4 .and 5-l open, .the hot air-passes throughthe pipe '35 and the duct 22 into the drying chamber. This airfmoves' transversely ofthe' chamber 'through the piled lumber to absorb moisture therefrom. The air,-now cooler, leaves the "drying chamber and passes through the'duct23 and the'pipe' 36-back to the heating chamber. -When the control valves are reversed, that is, the-valves 41--and 5 Lare closedand the valves-48 and 50 are "opened, the hotair passes through the pipes -35 and-45 andt-he duct 23into the chamben'an'd-the cooler air passes through the duct2'2-and the *pipes -46 and 36 back to l the heating chamber.

If-desired, natural circulation onlymay be used, 31' to ensure a positive movement oi the air.

'Thesawdust' burner unit 21 {directly heats-the air'inthe chamber 2 5*so that: a-m aximumamount of the heat generated.istrai'isferred to said-air. As the "lumber dries, the air in the circuit be- "comes laden with the-moistureextractedthere- -from. Thus the naturalfmoisturepf the 'WOOH is. utilized to, prevent -itf'from' drying too-rapidly, preventing checking-and splitting,- and it prevents the lumber from becoming -case "harden'ed'.ii. e., drier at' the surface "of each piece than 'injth e "interiorthereof. Should the air-inthesystembecome'too jmoist, ioneorm'ore'of the valve arrangements I 8 may be 'partially or completely {opened to permit some of [the moisture-laden air to 'escape. -If, '"onj the other hand,- the air becomes "toodry, 'steamfor atomized "water 'may *be injected *thereinto' through the nozzles "The setting'of the control valves*4l;'-48 501-a-njd 7 "5|; is arrangedfso-thaflhot airfiows into the drying chamber throughpne of theducts'for aftime, and then the setting-is changed to direct said hot air into the-chamber 'throug'lr'the opposite id uct for an equal time. By alternating*in' thismanner, :the lumber is "dried evenly on both sides hthereof; v d

No skill -is*requiredto operate this apparatus. The :hopperf'2 8 0i 'the sawdust burner unit needs to be filled and the settingof the -con'trol*valv'es 1 "Ihe-length'of time necessary for drying the lumber dependsupon the typeof Iu'mber an'd 'the degree of dryness required. -With this apparatus, however, -the drying *maytake longer --than 'the' kilns now in common 'usef'but this 'is very T desirable as' 'far as qua'lit'yof the finished products is concerne'd,-andthe T h g nessof construction and operation=-ofthis apparatus-eliminates the necessity or -dryingthe lumber in the least-pos- 2,358,423 sible time. The cheapness of operation and the completeness of operation and simplicity of this apparatus has the advantagesthat the drying chamber does not require any special construction and it may be of much lighter construction than the known kilns, since heat insulation is not required.

Various modifications may be made in this invention without departing from the spirit thereof or the scope of the claims and, therefore, the exact forms shown are to be taken as illustrative only and not in a limiting sense, and it is desired that only such limitations shall be placed thereon as are-disclosed in the prior art or are set forth in the accompanying claim.

What I claim as my invention is:

Lumber drying apparatus comprising a drying chamber having openings for the escape of moisture near the upper part thereof, air ducts at opposite sides of the chamber adjacent to the base and extending longitudinally thereof, each duct being formed with'openings in the top and being gradually reduced in cross section from one end to the other, a heating unit comprising a fuel burning chamberfa heatingchamber and a stack, the said heating chamber having a plurality of tubes through which the products of combustion are designed to pass, pipes connecting the ducts to the heating chamber, one of the ducts opening at the upper part of the heating chamber and the other duct opening into the lower part of the heating chamber, a force draft fan operably associated with one of the ducts to effect circulation through the same, a pair of transverse interconnecting pipes connecting the two ducts, each of said transverse pipes having a valve therein, control valves so arranged with respect to the transverse ducts that circulation of air may be caused to pass from one duct to the other in the drying chamber in either direction and means in one of the said ducts for adding moisture to the air.

CARLTON STONE. 

